The Field of the Invention
This invention relates to components for operation in ultra-pure environments and, more particularly, to novel systems and methods for providing long-lived pumps that are metal-free, ultra-pure, non-reactive, etc. for providing environments for hot, reactive or pure, liquids at elevated temperatures, with respect to ambient.
Non-reactivity is a critical function in systems managing, transporting, or relying upon fluids. Fluids include gases and liquids. Many industrial processes rely on liquids, that may damage, weaken, leach, or otherwise interact with metals, elastomeric polymers, and other common materials.
One industry that has suffered with the limited technology available to provide high purity and temperature is the semiconductor processing industry. For example, hot, deionized water is used in numerous processes. Impurities are measured in parts per billion. Some materials may be hot acids used in etching and cleaning processes. Transporting, holding, heating, and other procedures for managing ultra-pure water, acids, and the like, are problematic in several ways.
For example, pumps have traditionally been made of metal. Metals are commonly used in the support structures of the pumps. Regardless of the "stainlessness" of a metal, the purity requirements are not met by any known metals.
Polymers are often used for sealing members but may leach, react, degrade, or otherwise contaminate liquids. Moreover, polymers are typically not dimensionally stable. Polymers creep, stretch, yield, and otherwise become unreliable. Polymers (plastics, elastomers) respond to load, pressure, time, chemical environment, and, if any system failure occurs, may destroy any hope of reliability and "failing clean," failing to function yet leaving no contamination possible. Failures in the sealings may arise by creep or yielding of polymers. Leaks or other failures may expose materials during any failure. Accordingly, seals do not achieve perfect protection. The ability to avoid failures completely ranges from extremely difficult to impossible. Failures can be catastrophic if a system will not "fail clean."
Contaminants in trace amounts which exceed allowable limits may destroy a batch of product. Physical destruction is not required. Rendering a silicon wafer, or other high purity substrate material, unusable due to contaminant reaction with a surface can waste product output. Down time for decontamination may be even more costly in actual lost production.
What is needed is a fluid handling system that is clean to extremely high standards. All materials that may potentially contact contained fluids, even in the event of failures, should be pure and non-reactive. Materials should tolerate temperatures in the range of 1 degree Celsius to 180 degrees Celsius. In some acids, temperatures may range from 100 degrees Celsius to 180 degrees Celsius.
Thus, stability over a broad range of temperatures, reliability in service, long life under exposure to extreme of temperatures, pressure, and reactive agents, and the like must all be tolerated. Repeatability of designs, and reliable repeatability over the lifetime of all installed apparatus in the system are very desirable. Currently, the most reliable pump mechanisms still depend on elastomeric seals and metal structural supports. Pumps do not have sufficient life and do not "fail clean" in service. Upon failure, metals and elastomers are then exposed and are reactive. Thus, pumps still fail to maintain purity in failure or to operate reliably over many millions of cycles.
What is needed is a reliable, failclean, pump that operates over 10-50 million cycles, and that maintains purity, even in failure. Long term durability at elevated temperatures, pressures, and reactivities, without the threat of catastrophe at failure, is needed.